Implement Tray Icons

This commit implements the StatusNotifierItem protocol, and enables
swaybar to show tray icons. It also uses `xembedsniproxy` in order to
communicate with xembed applications.
The tray is completely optional, and can be disabled on compile time
with the `enable-tray` option. Or on runtime with the bar config option
`tray_output none`.

Overview of changes:
In swaybar very little is changed outside the tray subfolder except
that all events are now polled in `event_loop.c`, this creates no
functional difference.

Six bar configuration options were added, these are detailed in
sway-bar(5)

The tray subfolder is where all protocol implementation takes place and
is organised as follows:

tray/sni_watcher.c:
	This file contains the StatusNotifierWatcher. It keeps track of
	items and hosts and reports when they come or go.
tray/tray.c
	This file contains the StatusNotifierHost. It keeps track of
	sway's version of the items and represents the tray itself.
tray/sni.c
	This file contains the StatusNotifierItem struct and all
	communication with individual items.
tray/icon.c
	This file implements the icon theme protocol. It allows for
	finding icons by name, rather than by pixmap.
tray/dbus.c
	This file allows for asynchronous DBus communication.

See #986 #343

1 files changed, 11 insertions, 0 deletions

diff --git a/sway/config.c b/sway/config.c
index 85823953..e0b65615 100644
--- a/sway/config.c
+++ b/sway/config.c
@@ -69,6 +69,10 @@ static void free_bar(struct bar_config *bar) {
         }
         free(bar->mode);
         free(bar->hidden_state);
+#ifdef ENABLE_TRAY
+        free(bar->tray_output);
+        free(bar->icon_theme);
+#endif
         free(bar->status_command);
         free(bar->font);
         free(bar->separator_symbol);
@@ -1386,7 +1390,14 @@ struct bar_config *default_bar_config(void) {
         bar->separator_symbol = NULL;
         bar->strip_workspace_numbers = false;
         bar->binding_mode_indicator = true;
+#ifdef ENABLE_TRAY
+        bar->tray_output = NULL;
+        bar->icon_theme = NULL;
         bar->tray_padding = 2;
+        bar->activate_button = 0x110; /* BTN_LEFT */
+        bar->context_button = 0x111; /* BTN_RIGHT */
+        bar->secondary_button = 0x112; /* BTN_MIDDLE */
+#endif
         bar->verbose = false;
         bar->pid = 0;
         // set default colors